具有节点超导能隙的Ca(PtAs)(FeAs)单晶赝能隙谱中预形成库珀对模型的证据。

Evidence for a preformed Cooper pair model in the pseudogap spectra of a Ca(PtAs)(FeAs) single crystal with a nodal superconducting gap.

作者信息

Seo Y I, Choi W J, Kimura Shin-Ichi, Kwon Yong Seung

机构信息

Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of Korea.

Graduate School of Frontier Biosciences and Department of Physics, Graduate School of Science, Osaka University, Suita, 565-0871, Japan.

出版信息

Sci Rep. 2019 Mar 8;9(1):3987. doi: 10.1038/s41598-019-40528-3.

DOI:10.1038/s41598-019-40528-3

PMID:30850717

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC6408529/

Abstract

For high-T superconductors, clarifying the role and origin of the pseudogap is essential for understanding the pairing mechanism. Among the various models describing the pseudogap, the preformed Cooper pair model is a potential candidate. Therefore, we present experimental evidence for the preformed Cooper pair model by studying the pseudogap spectrum observed in the optical conductivity of a Ca(PtAs)(FeAs) (T = 34.6 K) single crystal. We observed a clear pseudogap structure in the optical conductivity and observed its temperature dependence. In the superconducting (SC) state, one SC gap with a gap size of Δ = 26 cm, a scattering rate of 1/τ = 360 cm and a low-frequency extra Drude component were observed. Spectral weight analysis revealed that the SC gap and pseudogap are formed from the same Drude band. This means that the pseudogap is a gap structure observed as a result of a continuous temperature evolution of the SC gap observed below T. This provides clear experimental evidence for the preformed Cooper pair model.

摘要

对于高温超导体而言，阐明赝能隙的作用和起源对于理解配对机制至关重要。在描述赝能隙的各种模型中，预形成的库珀对模型是一个潜在的候选者。因此，我们通过研究在Ca(PtAs)(FeAs)（T = 34.6 K）单晶的光导率中观察到的赝能隙光谱，给出了预形成的库珀对模型的实验证据。我们在光导率中观察到清晰的赝能隙结构，并观察了其温度依赖性。在超导（SC）态下，观察到一个超导能隙，能隙大小为Δ = 26 cm，散射率为1/τ = 360 cm，以及一个低频额外的德鲁德分量。光谱权重分析表明，超导能隙和赝能隙由同一个德鲁德带形成。这意味着赝能隙是在低于T时观察到的超导能隙连续温度演化所导致的能隙结构。这为预形成的库珀对模型提供了明确的实验证据。